JP5436023B2 - Fuel oil composition for diesel engines - Google Patents

Description

  The present invention relates to a fuel oil composition for a diesel engine, and more particularly to a fuel oil composition for a diesel engine provided with a feedback control mechanism that feedback-controls engine operating conditions.

Challenges required for automobile fuels have changed with the times, but in recent years, “fuels with low total CO ₂ emissions from fuel production to fuel consumption (WtW-CO2: Well to Wheel) (CO ₂ Measures) ”and“ Effective use and diversification of fossil fuels (security measures) ”are extremely important. For the former, in addition to the introduction of biofuels treated as carbon-free, it is necessary to aim to minimize WtW-CO2 by a combination of engine technology and fuel technology. That is, even if high-quality fuel is pursued for the purpose of reducing CO ₂ emissions from automobiles (TtW-CO2: Tank to Wheel), CO ₂ emissions in the manufacturing process (WtT-CO2: Well to Tank) If it becomes excessive, WtW-CO2 cannot be reduced. Therefore, it is necessary to pursue fuel quality that minimizes WtW-CO2.

In addition, for the latter (security measures), effective use of cracked diesel oil base (LCO) is important for diesel engine fuel due to changes in the demand structure of petroleum products (the drastic decrease in demand for heavy oil). It has become. In addition, as part of diversification measures for base materials, the use of non-petroleum oil sand-derived light oil base materials is also increasing. However, the light oil base and LCO derived from the oil sand are low-quality fuels with high aromatic content and low cetane number, and improve (upgrade) the quality to the light oil quality required by existing diesel engines. Therefore, a large amount of CO ₂ is generated in the production stage, and a significant increase in production cost is expected, which is not preferable from the viewpoint of economy.

  On the other hand, it is known that the required quality for diesel engine fuel varies greatly depending on engine specifications and control method. For example, by optimizing the compression ratio for each fuel for a series of fuels with different ignitability (high compression ratio is set for low ignitable fuel), the combustion efficiency between the fuels can be improved. It has been reported that the difference can be almost eliminated (Non-patent Document 1). In addition, by equipping an engine mechanism (feedback control mechanism) that detects the internal pressure of the engine, grasps the combustion state, and controls the fuel injection timing that matches the ignitability of the fuel, the ignitability of the fuel (for example, cetane number) ) Has been developed in order to prevent the change of) from excessively affecting the engine performance (Non-patent Document 2).

Hideyuki Ogawa, Fuel ignition and compression ratio dependency of a pre-charged charge compression engine, Int. J. et al. Vehicle Design, Vol. 41 no. 1/2/3/4, 2006 Mamoru Hasegawa, Study on Ignition Timing Control for Diesel Engine Using In-Cylinder Pressure Sensor, SAE Paper 2006-0180 (2006)

Therefore, considering the recent progress in engine technology, when trying to use low quality oil effectively by upgrading, instead of upgrading to the required quality of the engine based on the specifications and control of the existing diesel engine, Pursuing desirable quality by optimizing the engine and fuel is extremely important from the viewpoint of WtW-CO2 reduction. An example of studying the quality level based on this concept is setting the octane number of gasoline. Generally, since the compression ratio of the engine can be increased by increasing the octane number, the fuel efficiency of the automobile is improved, and the CO ₂ emission from the automobile is reduced. On the other hand, if high-octane gasoline is produced, CO ₂ emissions at the refinery will increase. Therefore, pursuing the optimization of fuel and engine, there will be an octane number that minimizes WtW-CO2, and the optimal octane number Setting is being considered.

Therefore, when using a low-quality gas oil base (light oil fraction derived from LCO or oil sand) as a starting material, and using hydrorefining as a means of upgrading the material, the degree of upgrading is determined by the engine that uses the fuel (operation It is necessary to have hydrorefining conditions that can produce fuel with properties that do not impair the operability and exhaust gas of the engine) that can adapt the conditions to the properties of the fuel and that do not cause excessive CO ₂ emissions from the engine. However, the more severe the hydrorefining conditions, the more CO ₂ emissions during production (WtT-CO2) will increase and the economics associated with production will deteriorate, so the degree (severity) will be as mild as possible. There is a need to.

Accordingly, an object of the present invention is to provide a fuel oil composition for a diesel engine that can ensure the quality required by the engine and that has a low CO ₂ emission during production.

  As a result of intensive studies to achieve the above object, the present inventors have found that a low-quality light oil base, particularly a light oil base having a cetane number of 30 or less and a total aromatic content of 50% by volume or more, An engine control mechanism capable of adapting the operating conditions to the fuel properties of the fuel obtained by hydrorefining so that the cetane number and the total aromatic content are in a specific range, with specific distillation properties It has been found that the use of the diesel engine can reduce WtW-CO2 without deteriorating the operability of the engine or increasing the amount of exhaust gas, and the present invention has been completed.

That is, the fuel oil composition of the present invention comprises a light oil base having a cetane number of 30 or less and a total aromatic content of 50% by volume or more, a hydrogen partial pressure of 3 to 15 MPa, a temperature of 250 to 420 ° C., a liquid space. Using hydrorefined oil obtained by hydrotreating under conditions of a speed of 0.3 to 10.0 hr ⁻¹ and a hydrogen / oil ratio of 100 to 2,000 L / L,
Cetane number of 34 to 50, total aromatic content of 10.0 to 45.0% by volume, boiling point range of 130 to 360 ° C, sulfur content of 50 mass ppm or less, density at 15 ° C of 0.800 to 0.880 g / Cm ³ , CO ₂ emission intensity (CO2I) is 0.072 (CO2-g / kJ) or less, and for diesel engines having a feedback control mechanism for feedback control of engine operating conditions It is a fuel oil composition.

  According to the fuel oil composition of the present invention, WtW-CO2 can be reduced without increasing the amount of exhaust gas such as particulate matter (PM) and NOx.

  Details of the present invention will be described below. The fuel oil composition for a diesel engine of the present invention has, for example, a quality obtained when a low quality oil such as a catalytic cracking light oil base or an oil sand derived light oil base is used as a raw material and the raw material is upgraded by hydrorefining. The fuel has the following properties, and is characterized in that it is used as a fuel for a diesel engine whose operating conditions can be adapted to the fuel properties.

<Density>
The fuel oil composition of the present invention has a density of 0.800 to 0.880 g / cm ³ . If the density of the fuel oil composition exceeds 0.880 g / cm ³ , the amount of particulate matter (PM) discharged increases and the environmental load cannot be reduced sufficiently. Further, if the density is too high, the atomization characteristics of the fuel are deteriorated and the combustion efficiency may be lowered. Therefore, the fuel oil composition of the present invention has a density of 0.880 g / cm ³ or less, preferably 0. 860 g / cm ³ or less. On the other hand, when the density is less than 0.800 g / cm ³ , the capacity-based fuel consumption rate is significantly deteriorated. Therefore, the fuel oil composition of the present invention has a density of 0.800 g / cm ³ or more, preferably 0.8. It is 820 g / cm ³ or more.

<Sulfur content>
The fuel oil composition of the present invention has a sulfur content of 50 mass ppm or less, preferably 10 mass ppm or less, more preferably 1 mass ppm or less. Since the fuel oil composition of the present invention has a sulfur content of 50 ppm by mass or less, there are few sulfur oxides as combustion products, which can contribute to a reduction in environmental burden. Further, since the sulfur content poisons the exhaust gas purification catalyst, the reduction of the sulfur content can contribute to the reduction of the environmental load through the maintenance of the performance of the exhaust gas purification catalyst. Furthermore, in a vehicle equipped with a NOx occlusion reduction catalyst, fuel is used for regeneration of sulfur poisoning of the catalyst. Therefore, reduction of the sulfur content also contributes to improvement of fuel consumption. And since these effects are so remarkable that a sulfur content is low, the sulfur content in the fuel oil composition of this invention becomes like this. Preferably it is 10 mass ppm or less, More preferably, it is 1 mass ppm or less.

<Distillation properties>
The fuel oil composition of the present invention has a boiling point range of 130 to 360 ° C, preferably 150 to 340 ° C. If the distillation temperature exceeds this range, an adverse effect on engine performance is observed. More specifically, when the initial distillation temperature (IBP) is lower than 130 ° C., fuel vapor is generated in the fuel injection system under a high temperature condition, and a necessary fuel injection amount cannot be secured. In addition, if the initial distillation temperature is too low, the danger associated with fuel handling and vaporization of the fuel in the fuel supply system increases, so the initial distillation temperature needs to be 130 ° C. or higher. On the other hand, if the end point (EP) of the fuel oil composition exceeds 360 ° C., the amount of particulate matter (PM) discharged increases and the environmental load cannot be reduced sufficiently. Further, if the end point is too high, a part of unburned fuel flows into the oil pan and easily causes dilution of the engine oil. Therefore, the end point of the fuel oil composition of the present invention needs to be 360 ° C. or less. It is. Although not particularly limited, the fuel oil composition of the present invention preferably has an end point of 300 ° C. or higher from the viewpoint of maintaining the lubricity of the fuel injection pump and preventing wear of the fuel injection nozzle.

<Cetane number>
The fuel oil composition of the present invention has a cetane number of 34 or more, preferably 36 or more. This is because if the cetane number is less than 34, a reduction in combustion efficiency cannot be avoided even if the engine control system is optimized in accordance with the ignitability of the fuel. In addition, if the cetane number is too low, combustion fluctuations increase remarkably due to deterioration of ignitability, particularly under low temperature conditions. is there. On the other hand, if the cetane number exceeds a certain value, the ignition delay accompanying the improvement of the cetane number cannot be shortened. Therefore, it is meaningless from the standpoint of engine performance to increase it higher than necessary. In addition, increasing the cetane number not only increases CO ₂ emissions during production, but also increases the production price of fuel. From the economic point of view, it is necessary to set the minimum cetane number required by the engine. In an engine in which the operating conditions can be adapted to the fuel properties, the cetane number of the fuel oil composition is 50 or less, preferably 47 or less.

<Aromatic>
The fuel oil composition of the present invention has a total aromatic content of 45.0% by volume or less, preferably 40.0% by volume or less, more preferably 35.0% by volume or less. This is because when the aromatic content in the fuel oil composition increases, the amount of particulate matter (PM) discharged increases and the environmental load cannot be reduced sufficiently. Further, although not particularly limited, since aromatics having two or more rings have a greater influence on the increase in PM emission than single-ring aromatics, aromatics having two or more rings in the fuel oil composition of the present invention. The group content is preferably 11% by volume or less, more preferably 5% by volume or less. In petroleum-based light oil, there is a general correlation between the aromatic content and density, and in fuels with both high density and aromatic content, exhaust gas (especially PM) is significantly deteriorated. In the density fuel, the total aromatic content is desirably 40.0% by volume or less.

<CO ₂ emission intensity (CO2I)>
The fuel oil composition of the present invention has a low carbon dioxide emission during combustion, and the following formula (1):
CO2I = 1000 × {(16 × 2 + 12) / 12} × (C / 100) / (true calorific value)} (1)
[In the formula, C is the mass ratio (%) of carbon obtained by elemental analysis, and the true calorific value (kJ / kg) is expressed by the following formula (2):
True calorific value (kJ / kg) = 4.184 × [8100 × C / 100 + 29000 × {H / 100−O / (8 × 100)} + 2200 × 0 / 1000000−600 × 0/1000000] (2 )
{In the formula, C is a mass proportion (%) of carbon obtained by elemental analysis, H is a mass proportion (%) of hydrogen obtained by elemental analysis, and O is a mass proportion (%) of oxygen obtained by elemental analysis. The calculated CO ₂ emission unit (CO2I) defined in the above is 0.072 (CO2-g / kJ) or less, preferably 0.071 (CO2-g / kJ). It is as follows. In order to reduce the amount of CO ₂ emitted from the engine, the CO ₂ emission amount per unit calorific value of the fuel oil composition needs to be small, and therefore the CO _{2 I} of the fuel oil composition of the present invention is 0.072. (CO2-g / kJ) or less.

(Preparation of fuel oil composition)
The fuel oil composition of the present invention has a low quality light oil base material such as a cracked light oil base material (LCO) or a light oil base material derived from oil sand, in particular, a cetane number of 30 or less so as to satisfy the above properties. Thus, it can be prepared by hydrorefining using a light oil base having a total aromatic content of 50% by volume or more as a raw material. That is, a gas oil having a specific aromatic concentration, for example, a cracked gas oil fraction (for example, a fraction having a boiling point of 120 to 400 (° C.)) is hydrorefined under specific conditions to have an appropriate cetane number. In addition, a gas oil fraction having a low residual sulfur content can be obtained. Furthermore, it is also effective to divide the reaction tower into two groups and provide a known hydrogen sulfide removing device in the middle to remove hydrogen sulfide generated in the hydrodesulfurization step. In addition, the fuel oil composition of the present invention is prepared by using a normal reactor in which a fixed bed type catalyst is formed in a high-pressure flow reactor and treating a light oil fraction under relatively mild reaction conditions. Can do. Therefore, according to the present invention, for example, surplus cracking gas oil can be economically converted to a gas oil fraction such as diesel fuel. A specific method is described below.

As hydrorefining conditions, the hydrogen partial pressure is 3 to 15 MPa, preferably 4 to 12 MPa, more preferably 5 to 10 MPa, and the temperature is 250 to 420 ° C., preferably 280 to 400 ° C., more preferably 300 to 380. ° C, the liquid space velocity is 0.3 to 10.0 hr ^-1 , preferably 0.4 to 7.0 hr ^-1 , more preferably 0.5 to 5.0 hr ^-1 , and the hydrogen / oil ratio is 100 to 2,000 L / L, preferably 200 to 1,700 L / L, more preferably 300 to 1,500 L / L.

If the pressure (hydrogen partial pressure) is less than 3 MPa, the desulfurization activity of the catalyst is lowered and the nuclear hydrogenation activity is lowered, and the desired cetane number and sulfur concentration cannot be achieved. Since the nuclear hydrogenation reaction proceeds, the amount of CO ₂ emission during the production of fuel oil increases, which is not preferable. In addition, if the reaction temperature is less than 250 ° C., the desulfurization activity and nuclear hydrogenation activity of the catalyst are low. Conversely, if the reaction temperature exceeds 420 ° C., the catalyst activity deteriorates rapidly due to carbon deposition, and the equipment cost increases. Operating costs increase. In addition, when the liquid space velocity exceeds 10.0 hr ⁻¹ , the contact time between the catalyst and the raw material oil becomes too short, and the desulfurization reaction and the nuclear hydrogenation reaction are not sufficiently performed. On the other hand, if it is less than 0.1 hr ⁻¹ , the contact time becomes excessively longer than necessary, and the processing efficiency decreases. Further, if the hydrogen / oil ratio is less than 100 L / L, the desulfurization reaction does not proceed sufficiently. Conversely, if the hydrogen / oil ratio exceeds 2,000 L / L, excessive hydrogen is consumed, which increases the processing cost. It is uneconomical.

  Although it does not specifically limit as a hydrorefining catalyst used for preparation of the fuel oil composition of this invention, The catalyst which carry | supported the metal on the support | carrier illustrated below is preferable. Various carriers can be used, and examples thereof include inorganic oxides such as silica, alumina, boria, magnesia, titania and zeolite. These inorganic oxides may be used alone or in combination of two or more.

  The hydrorefining catalyst used for the preparation of the fuel oil composition of the present invention is preferably a catalyst in which at least one metal selected from Group 6 metals and Group 8 metals is supported on the carrier. Examples of the Group 6 metal include molybdenum and tungsten. Examples of the Group 8 metal include cobalt, nickel, platinum, palladium, rhodium, ruthenium, iridium, indium, osmium, and iron. Furthermore, the hydrorefining catalyst may contain phosphorus, boron, zinc, zirconia, or the like, in addition to the active metal composed of Group 6 metal and Group 8 metal, as necessary.

  The average pore diameter of the catalyst is preferably 60 to 120 mm. If the average pore diameter is too large, the diffusibility of the sulfur compound into the pores is good, but the specific surface area of the catalyst is small, so the desulfurization activity is reduced, which is not preferable. Since it becomes high and desulfurization activity falls similarly, it is not preferable.

The fuel oil composition of the present invention uses the hydrorefined oil obtained by the above hydrorefining, and further adds one or more kinds of normal paraffin-based, isoparaffin-based and naphthenic base materials and solvents. It can also be prepared. Examples of such base materials and solvents include GTL that can be manufactured from natural gas through synthetic gas (hydrogen and carbon monoxide) and Fischer-Tropsh reaction (FT synthesis), and refined oils and fats derived from vegetable oil. Examples include HVD that can be produced by hydrorefining or hydrocracking with a hydrogenation catalyst such as those used in the above, and SHNP that is a normal paraffinic solvent that can be purchased through JOMO Sun Energy. These base materials and solvents have features such as extremely low aromaticity (or no inclusion), good ignitability, and low CO ₂ emission basic unit. In order to obtain desirable fuel properties, It can be used by mixing with low quality hydrorefined oil. However, since these substrates and solvents have a higher CO ₂ emission during production than petroleum-based substrates, the amount added is a mixture of these substrates and solvents and low-grade hydrorefined oil. so as not to exceed the CO ₂ emissions CO ₂ emissions discharged from the engine in the preparation, i.e., such that the total CO ₂ emissions from the production of fuel to consumption is not increased, the amount of the minimum necessary It is necessary to.

<Additives>
The fuel oil composition obtained by the above method includes known fuels such as low-temperature fluidity improvers, wear resistance improvers, cetane number improvers, antioxidants, metal deactivators, and corrosion inhibitors. Additives may be added. As the low temperature fluidity improver, an ethylene copolymer or the like can be used. In particular, a vinyl ester of a saturated fatty acid such as vinyl acetate, vinyl propionate or vinyl butyrate is preferably used. As the wear resistance improver, for example, a long-chain fatty acid (carbon number 12 to 24) or a fatty acid ester thereof is preferably used, and the wear resistance is sufficient with an addition amount of 10 to 500 ppm by mass, preferably 50 to 100 ppm by mass. Will improve. In addition, as the cetane number improver, alkyl nitrate is widely used with an addition amount of 100 to 5000 ppm by mass, but peroxide (for example, ditertiary butyl peroxide) may also have an effect of improving cetane number. ,It is valid.

<Diesel engine with feedback control mechanism>
The above-described fuel oil composition of the present invention is used in a diesel engine having a feedback control mechanism that feedback-controls engine operating conditions. The feedback control mechanism is not particularly limited as long as the engine operating conditions can be feedback controlled. For example, as the feedback control mechanism, an operating condition control means for controlling the operating condition of the engine, a combustion condition detecting means for detecting the actual combustion state of the fuel, and the actual combustion condition of the fuel become the target combustion condition. As described above, there is a feedback control mechanism including feedback control means for performing feedback control on the operation condition control means. Here, examples of the operating condition of the engine include a compression ratio and fuel injection pattern control.

Since the diesel engine with the feedback control mechanism includes a mechanism for feedback control of the operating condition of the engine, the allowable fuel property range is wide, and the fuel that does not satisfy the requirement property of the conventional diesel engine can be used. Although the above-described fuel oil composition of the present invention does not satisfy the requirements of a conventional diesel engine, it can be used in a diesel engine with a feedback control mechanism in order to satisfy the requirements of a diesel engine with a feedback control mechanism. The fuel oil composition of the present invention described above, since CO ₂ emissions during production in refineries is small as compared with the conventional gas oil, the total CO ₂ emissions from the production time of CO ₂ emissions and engine If in saw than conventional light oil, it can be reduced WtW-CO2 (CO ₂ emissions in total).

  As a diesel engine with a feedback control mechanism, a pressure sensor (for example, a method provided in a fuel injection device known in a fuel injection device) mounted in a combustion chamber and a crank angle detector are used to record a pressure history in the combustion chamber. Measure and calculate combustion characteristics such as ignition delay, maximum value of heat generation rate, maximum value of pressure rise rate, and adjust fuel injection characteristics (for example, pilot injection timing and its injection amount) An engine that controls the effect of changes in fuel properties on internal combustion is preferred.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

<Preparation of light oil composition>
First, fuel oil compositions (fuel-1 to fuel-8) used for the evaluation test were prepared as follows. Table 1 shows analytical values of the composition of these fuel-1 to fuel-8.

・ Fuel-1: Catalytic cracking gas oil base material (LCO) ... starting material

・ Fuel-2: Fuel A obtained by hydrocracking LCO [A catalyst consisting of LCO as a raw material and Ni, Mo, P supported on an alumina carrier (hydrorefining catalyst) in the A tower, a carrier comprising alumina and USY zeolite A catalyst (hydrocracking catalyst) carrying Ni and Mo is used in column B, reaction temperature 360 (° C.) in column A, reaction temperature 400 (° C.) in column B, and hydrogen partial pressure 5 (MPa). , 140 to 360 (° C.) distillate of a product hydrocracked at a hydrogen / oil ratio of 1400 (NL / L) and an oil flow rate of 0.5 (1 / h). The composition of the hydrorefining catalyst is 12.3% by weight of Mo, 3.5% by weight of Ni, 2.0% by weight of P, 43.3% by weight of Al, and the composition of the hydrocracking catalyst is Mo 7.1. % By weight, 3.0% by weight of Ni, 15.8% by weight of Si, and 23.5% by weight of Al. Further, when the pore characteristics of the hydrorefining catalyst and hydrocracking catalyst were measured by a nitrogen gas adsorption method, the hydrorefining catalyst had a specific surface area of 185 m ² / g and a pore diameter of ^{2 to} 60 nm. The pore volume is 0.415 mL / g, the center pore diameter is 7.9 nm, and the hydrocracking catalyst has a specific surface area of 387 m ² / g and a pore volume in the range of 2 to 60 nm. Was 0.543 mL / g, and the median pore diameter was 9.6 nm.

Fuel-3: Fuel B obtained by hydrorefining LCO [In the presence of the catalyst used for the production of fuel-2 using LCO as a raw material, reaction temperature 320 (° C.) in tower A, reaction temperature in tower B 355 (° C.), hydrogen partial pressure 7 (MPa), hydrogen / oil ratio 1400, oil-purified product 140-360 (° C.) distillate]

Fuel-4: Fuel C obtained by hydrorefining LCO [using LCO as a raw material, in the presence of Ni, Mo-based catalyst, reaction temperature 340 (° C.), hydrogen partial pressure 8 (MPa), hydrogen / oil ratio 300, 140-360 (° C) distillate of hydrorefined product with oil flow rate 0.9 (1 / h)]

・ Fuel-5: GTL produced by FT synthesis with 96% by volume of the above-mentioned fuel-4 {Moss gas product purchased through JOMO Sun Energy Co., Ltd. 4% by volume of cetane number = 75, sulfur <1% by mass, aromatic <1% by mass} was mixed, and 600 ppm by volume of alkyl nitrate cetane improver was added to the mixed fuel.

Fuel-6: Fuel D obtained by hydrorefining LCO [LCO is used as a raw material in the presence of Ni, Mo-based catalyst, reaction temperature 300 (° C.), hydrogen partial pressure 8 (MPa), hydrogen / oil ratio 300, 140-360 (° C) distillate of hydrorefined product with oil flow rate 0.9 (1 / h)]

Fuel-7: Fuel obtained by hydrocracking a vacuum gas oil fraction obtained by distillation under reduced pressure [hydrogen using a vacuum gas oil as a raw material, the above-mentioned hydrorefining catalyst as the A tower, and Pt and Pd supported on the USY zeolite carrier Using the cracking catalyst in the B tower, the reaction temperature 320 (° C.) in the A tower, the reaction temperature 210 (° C.) in the B tower, the hydrogen partial pressure 5 (MPa), the hydrogen / oil ratio 450 (NL / L) , 140-360 (° C.) distillate of the product hydrocracked at an oil flow rate of 1.0 (1 / h)]. The composition of the hydrocracking catalyst was 0.71 wt% Pd, 0.25 wt% Pt, 22.6 wt% Si, and 16.7 wt% Al.

・ Fuel-8: Commercial JIS No. 2 diesel oil

<Fuel property analysis>
・ Density: JIS K2249 “Density test method for crude oil and petroleum products”
・ Distillation properties: JIS K2254 "Distillation test method"
・ Sulfur content: JIS K2541-6 “Sulfur content test method (ultraviolet fluorescence method)”
-Total aromatic content, aromatic content of 2 or more rings: Petroleum Society method JPI-5S-49-97 "Petroleum products-Hydrocarbon type test method-High performance liquid chromatographic method"
-Cetane number: JIS K2280 "Petroleum products-Fuel oil-Octane number and cetane number test method and cetane index calculation method"
-H component and C component: Measured using an organic element analyzer (CHN-1000 type manufactured by LECO).
CO ₂ emission basic unit (CO2I): Calculated according to the above formulas (1) and (2) using the mass ratio of carbon, the mass ratio of hydrogen, and the mass ratio of oxygen determined by elemental analysis.

<Test engine specifications and operating conditions>
Number of cylinders: 1
Displacement: 1007 (cm ³ )
Compression ratio: Set to 16 and 20 Fuel injection system: Pilot injection and variable main injection timing Injection pressure: 150 (MPa)

<Engine performance evaluation method>
Combustion analysis: Analyzing combustion behavior after detecting the pressure in the combustion chamber with a pressure sensor Exhaust gas: Analyzing PM, NOx, HC, CO, CO ₂ in exhaust gas using an exhaust gas analyzer manufactured by Horiba

<Methods for evaluating CO ₂ emissions and emissions from engines, and CO ₂ emissions during production>
The compression ratio is set to 16 and 20, the rotational speed is fixed to 1300 (rpm), and the fuel consumption rate (the fuel consumption amount and the figure are shown) of each fuel while searching for the fuel injection pattern that maximizes the combustion efficiency with each fuel Calculated from the mean effective pressure). For each fuel, the “minimum amount of CO ₂ emitted from the engine” was determined from the fuel consumption rate measured under conditions that maximize the combustion efficiency and the H / C ratio of the fuel. Furthermore, CO ₂ in the exhaust gas was directly measured, and the measurement result was confirmed. On the other hand, the exhaust gas was measured under engine conditions where the fuel consumption rate was minimized.

In addition, the evaluation of CO ₂ emissions from each fuel in the engine test is based on the commercially available diesel oil JIS No. 2 diesel oil (Fuel-8) as a reference (×) for fuel with more CO ₂ emissions than this, equivalent fuel Is represented by (Δ), a small amount of fuel is represented by (◯), and a fuel with a large fluctuation in combustion and poor operability and extremely deteriorated fuel consumption is represented by (XX). In addition, exhaust gas is evaluated relative to commercial diesel oil, fuel with a large amount of exhaust gas (mainly PM) (×), equivalent fuel (△), fuel with small amount (○), A large amount of fuel was designated as (XX).

On the other hand, CO ₂ emissions during production were exhausted at refineries when producing fuel-6, which is the mildest hydrorefining condition, based on conditions such as temperature and hydrogen consumption that are conditions for hydrotreating LCO. based on the amount of CO _2, relatively evaluated CO ₂ emissions from the fuel production, CO ₂ emissions and less fuel (○), CO ₂ emissions increment minor fuel (△), The fuel whose CO ₂ emission was remarkably increased was designated as (x). These results are shown in Table 1.

An engine that can adapt the operating conditions of the engine to the fuel properties is more robust to changes in the fuel properties and can tolerate a wider range of properties than existing engines, but LCO alone (Fuel-1) Then, since hydrorefining is not performed, the evaluation of CO ₂ emission during production is (◯). However, in addition to the remarkable deterioration of operability, the amount of exhaust gas increases remarkably, so that it cannot be used. Also, the fuel CO ₂ emissions during manufacturing was purified hydrogenated with relatively little mild conditions (fuel -4, fuel -6) In addition to the deterioration of exhaust gas from the engine, CO ₂ emissions Since it increases, it is not an acceptable quality level.

In the fuel with increased severe Rithy hydrotreating (fuel -2, fuel -3), the operation of the engine, the amount of exhaust gas, CO ₂ emissions, it is equivalent to approximately commercial diesel (fuel -8), the engine It has sufficient quality as a fuel for use. In addition, even fuel processed under hydrorefining conditions equivalent to that of Fuel-4 can be reformed to the minimum (to minimize CO ₂ during production) for the purpose of improving the cetane number and reducing the aromatic content. By doing so, the fuel quality is acceptable (Fuel-5). On the other hand, the fuel -7 enhanced further Severe Rithy hydrorefining, a relatively small exhaust gas from the engine, and although CO ₂ emissions was slightly less, remarkably many CO ₂ emissions during manufacturing In addition, it is inferior from the viewpoint of economics related to fuel production, and is inferior to the above-described fuel-2 and fuel-3, which comprehensively judge from fuel production to consumption. That is, it is determined that the fuel-7 is of excessive quality.

  Therefore, when comprehensively judging from the production to consumption of fuel, the fuel desirable for an engine having a mechanism capable of controlling the combustion in the engine is the fuel and hydrogenation whose hydrorefining degree is about fuel-2 or fuel-3. A fuel having a fuel quality of about fuel-5 by reforming with additives in addition to controlling the refining conditions is optimal.

Claims (1)

A gas oil base having a cetane number of 30 or less and a total aromatic content of 50% by volume or more, a hydrogen partial pressure of 3 to 15 MPa, a temperature of 250 to 420 ° C., and a liquid space velocity of 0.3 to 10.0 hr ⁻¹ , Using a hydrorefined oil obtained by hydrorefining under a hydrogen / oil ratio of 100 to 2,000 L / L,
Cetane number of 34 to 50, total aromatic content of 10.0 to 45.0% by volume, boiling point range of 130 to 360 ° C, sulfur content of 50 mass ppm or less, density at 15 ° C of 0.800 to 0.880 g / Cm ³ , CO ₂ emission basic unit is 0.072 (CO ₂ -g / kJ) or less, fuel oil composition for diesel engine having feedback control mechanism for feedback control of engine operating conditions object.